Railway traffic controlling apparatus



1939- c. w. FAILOR RAILWAY TRAFFIC CONTROLLING APPARATUS Filed'Jan. 25, 1958 2 Sheets-Sheet 1 H15 ATTORNEY Oct.'l0, 1 c. w. FAILOR RAIL'AY TRAFFIC CONTROLLING APPARATUS 2 Sheets-Sheet 2 Filed Jan. 25, 1938 A g 3 m A m IN NTOR Cilarl .Failor H [S ATTORNEY Patented Oct. 10, 1939 UNITED STATES PATENT OFFIE RAILWAY TRAFFIC CONTROLLING APPARATUS Application January 25, 1938, Serial No. 186,835

16 Claims.

My invention relates to railway trafiic controlling apparatus suitable for application to both steam and electric propulsion railroads and it has special reference to the organization of the trackway portions of such apparatus into systems of the class wherein either or both train-carried governing devices and wayside signals are controlled by coded energy transmitted through the track rails.

One feature of my invention resides in the provision of a novel and improved form of such organization which, in particular, facilitates application of the traffic-controlling apparatus to automatic signal blocks which contain out sections such as are occasioned by highway crossings,

interlocked switches or the like. Another feature resides in a novel utilization of steady energy for rapidly clearing out or detectively operating the track circuits of such cut sections upon their being vacated by a train. An additional feature resides in the provision of an automatic traincontrol system of the foregoing character which is self-protecting against false clear signal indications due to broken-down rail joints. A further feature involves the provision of decoding equipment having energy-supply circuits arranged in a novel manner.

I shall describe one form of railway trafiic controlling apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1a and lb are diagrammatic views which when placed end to end in the order named represent a stretch of railway track equipped with trafiic controlling apparatus embodying my invention; Fig. 2 is a representation of a portion of one of the signallocation equipments of Figs. la-b showing the decoding transformer thereof connected to receive rectified energy directly from the codetransmitting line circuit; and Fig. 3 is a diagrammatic showing of one manner in which steady energy of an elevated voltage may be supplied to the rear portion of a cut signal block.

Referring to the drawings, in the several views of which like reference characters designate corresponding parts, the improvements of my invention are there disclosed as being incorporated in a combined continuous cab signaling and automatic block signaling system for a track |2 over which trafl'ic' moves in the single direction designated by the arrows. The rails of the protected stretch of this track are, in the customary manner, divided by insulated joints 3 into a number of sections D--E, E-Ea, Ea--F', etc., each of which is identified with a track circuit of conventional character.

The particular stretch of track represented is intended for use in a railway system employing electric propulsion and for this reason impedance 5 bonds 4 of the usual form are provided at each pair of insulated joints to conduct propulsion current therearound. It will be apparent, however, that the apparatus of my invention is equally well suited for use on a steam road in which application the bonds 4 would, of course, be omitted.

In the protected stretch of track represented in the diagram, the locations D, E and F mark the points of main signal block division, while the location Ea represents a subdivision of one of these main signal blocks. This particular subdivision is occasioned by a highway H which crosses the track within the confines of the block EF and with which the usual crossing protective signals I 3 are associated. Insofar as the improvements of my invention now about to be disclosed are concerned, however, the subdivision at location Ea might also be occasioned by interlocked' switches (not shown) or anything else which requires that the signal block be divided into two or more sections.

Positioned at the entrance of each of the main signal blocks D--E, EF, etc. is a. wayside signal S which is adapted to indicate to an approaching train the nature of the traffic conditions in the blocks immediately ahead. The particular signals shown by way of illustration at the locations D, E and .F are two-arm semaphore devices and each is adapted to show any one of the four different aspects which respectiveiy signify the indications of clear, caution, slow and St p.

The block subdividing location represented at Ea, being within the confines of the block EF which is protected by signal Se, has no wayside signal other than the highway crossing protective devices lslassociated with it.

The rails of each of the referred to sections of track form a part of a track circuit which is adapted to transmit train control energy in the usual manner. In the particular arrangement represented, each of these track circuits further includes a track transformer TT connected, through the usual current limiting reactor I4, with the rails thereof at the trafiic leaving or exit end of the section and the control winding l of a track relay TR which is installed at the traffic entering end of the section.

Through the transformers T1 the track cir- 5s cuits are supplied with operating energy of a commercial signal frequency derived from a suitable alternating current source designated in the diagrams by the terminals B and C. Ordinarily cycle power is used for this purpose, such use making the system universally applicable to both electric and steam railroad operation and avoiding the possibility of interference from 60 or 25 cycle commercial or power circuits. Distribution of this power to the equipment at the several track circuit division-locations is eifected in any suitable manner as by the aid of a transmission circuit (not shown) extending along the right-of-way.

The energy which each transformer TT feeds to the running rails at the exit end of the associated track section is interrupted or coded a definite number of times per minute according to the traffic conditions ahead. Such alternate opening and closing of the rail supply circuit is effected at each of the signal locations D, E and F, etc. by a code transmitter CT there installed in the manner represented.

Each of the transmitters shown by Way of illustration is provided with three circuit-makingand-breaking contacts 80, I20 and I80 arranged for selective inclusion in the energizing circuit of the associated track transformer. These contacts are continuously actuated by a motor or other suitable mechanism (not shown in detail) at three different speeds which, for purposes of explanation, Will be assumed to be such as respectively to provide slow, caution and clear codes of 80, I20 and I80 energy pulses per minute. In the improved arrangement herein disclosed, all of these transmitters operate continuously, actuating energy therefor being constantly supplied from source B-C.

Selection of which one of the three coding contacts above named is included in the energizing circuit of the associated track transformer TT is effected by contacts I6 of three decoding relays H, J and JA which form a part of the equipment installed at each of the wayside signal locations D, E, F, etc. Included in the referred to transformer energizing circuit are the supply source terminals B and C and a conductor H extending from the primary winding of the transformer to the relay contacts.

When relays H and J or JA are actuated, the track transformer receives energy of the I80 or clear code through a circuit which includes coding contact I80 and conductor I0. When relay H only is actuated, the transformer circuit includes coding contact I20 and conductor is. Under this condition, the track circuit is supplied with energy of the I20 or caution code. Finally, when decoding relay H is unac tuated, energy of the 80 or slow code is supplied to the trackway through a circuit which includes coding contact 80 and conductor 20.

In addition to thus selecting the coding of the energy which is supplied to the track circuit to the rear, the decoding relays H, J and JA at each of the signal locations also control, through other contacts 22, the operation of the associated wayside signal S. The contacts last named are included in signal circuits which, through conductors 23 and 24, derive their energization from any suitable source of power designated in the diagrams by the terminals plus and minus.

When all three of the decoding relays are unactuated none of the signal circuits is energized and the controlled signal then displays the indication of stop. When relay H only is picked up, the circuit including conductor 25 is energized and the controlled signal is caused to show the slow indication. When relay J is also picked up the circuits including conductors 25 and 2? are energized causing the controlled si nal to show the caution indication. Finally, when relays H and JA are actuated and relay J is unactuated the circuits including conductors 25 and 20 are energized causing the controlled signal to display the clear indication.

The particular one of the four just described positional combinations which is assumed by the decoding relays at each signal location is determined by the character of the energy which is transmitted to a decoder supply transformer 28 through circuits presently to be described. From this transformer actuating current is supplied through a rectifier 29 to a master or code-following relay CR. This relay is provided with a contact 30 which is included in a pole-changing circuit for the primary winding of a decoding transformer DT. By this circuit the transformer DT is supplied, from any suitable source designated in the diagrams by the terminals plus and minus, with pulses of direct current energization at trackway code frequency.

These pulses cause to be induced in the secondary winding of the decoding transformer an alternating voltage of corresponding code frequency which through frequency-selective circuits 32 supplies actuating current to one or more of the decoding relays H, J and JA.' As represented, these relays are of the direct-current type and, as is shown in Fig. 2, the energizing circuit for each includes a full-wave rectifier 33. All three of these rectifiers derive energization from the secondary Winding of the decoding transformer DT.

In the case of relay H, the rectifier supply circuit includes a reactor 34 and is responsive to coded energizing pulses having frequencies cor responding to all three of the named 80, I20 and I80 trackway codes. In the case of relay J, the supply circuit includes a capacitor 31 and a reactor 39 which are so interrelated as to pass enough current to actuate the relay only when energizing pulses of the I20 code frequency are received from the transformer DT. In the case of relay JA, the supply circuit includes a capacitor 35 and a reactor 36 designed to be resonant at the I80 code frequency and to energize the relay only when the decoding transformer passes pulses at the rate of per minute.

The manner in which the decoding equipment operates will have become more or less evident from the foregoing description. When the equipment receives no energy at all or uncoded steady energy, relays H, J and JA all remain unactuated causing the associated signal S to show stop and the associated code transmitter CT to supply the track circuit to the rear with energy of the ill or slow code. When the received energy is of the 80 code, relay H only actuates to cause the controlled signal to display slow and the rear track circuit to be supplied with energy of the I20 or caution code. When the received energy is of the I26 code, the controlled signal shows caution and the rear track circuit receives energy of the I80 or clear code as a result of relay H and J being actuated. Finally, when the decoding apparatus receives energy of the E80 code, relays H and JA are actuated and relay J is unactuated, thereby causing the controlled signal S to display clear and the rear track circuit to be supplied with energy of the I80 code.

The particular track circuits represented function in the ordinary manner. As long as a particular track section is vacant, the rails thereof transmit train-control energy of one of the previously described codes to the associated track relay TR and thereby maintain that relay actuated. When, however, a train enters the section, the usual interconnection of the rails which its wheels and axles effects deprives the relay of this energy thereby causing it to open its contacts and initiate control operations further to be described.

As an additional result of the track circuit shunting, coded current is drawn from the transformer T1 at the exit end of the section through the rails ahead of the train. This current, in turn, causes signals (not shown because of their well-known character) carried in the cab of the train locomotive to provide the engineman with a continuous indication of advance traffic conditions. In a typical form of cab-signaling equipment, such indication results from the signals being controlled by an amplified measure of the rail-current proportional voltages which are induced in the usual pick-up apparatus mounted on the engine front and just above the running rails.

If the rail current is of the I80 code, the thus controlled cab signals show clear; if of the I20 code, the signals show caution; and if of the SE code, the cab signals display the slow indication. If the track section is already occupied by another train, the coded current is shunted by the train ahead and does not reach the following train. Under this condition, the indication of stop is given in the cab. This indication is also given if steady or uncoded track circurrent is flowing through the rails.

Considering further the track relays represented at TR, each of these is shown as being of the centrifugal frequency-selective type. In addition to the control winding I, already described as ..eing connected to the rails of the associated track, each relay is provided with a local winding 8 which also is arranged to receive energization from the alternating-current source BC. These two windings form a part of an induction motor which operates the relay contacts by rotating a fly ball mechanism 9. As long as this mechanism is at rest, the contacts occupy their downward or unactuated positions. When, however, the device is rotated the fly balls move outwardly by centrifugal action and this movement raises the relay contacts.

The contacts reach their fully actuated or front-closed positions only when the speed of this rotation is of the high value produced by energiaation of the relay windings from the I cycle or other signal-frequency supply circuit B--C. As any energy of the conventional 25 cycle electric-propulsion frequency which may enter the relay, as under unbalanced track circuit conditions in electrified territory applications, is incapable of producing the critical speed above referred to, contact closure is not possible due to stray propulsion or other comparable interference currents.

The rotative mechanism 9 and its driving Inotor possess considerable inertia characteristics and because of these a track relay of the type shown at TR, will maintain its contacts in their iront-closed positions when its windings I and 8 are simultaneously energized not only by steady I00 cycle or other sufiiciently high carrier-wave frequency. This permits the relay to hold its contacts in their front-closed positions as a result of receiving coded energy from the transmitting device CT. Should, however, energy be applied to only one of the windings, the effect will be one of retardation or braking of the rotative speed which reduces it at a rate more rapid than normal.

For the purpose of supplying the local winding 8 of each track relay TR and the associated decoding equipment with energy of the same character or coding as is that which the control winding 1 of the relay receives from the rails of the associated track circuit, I provide a line circuit which includes a pair of conductors 38 and 40 carried along the right-of-way in any suitable manner, as on poles. These conductors connect the winding 8 and the contacts 42 and 44 of each track relay TR with the circuit through which the track transformer TT at the exit end of the associated section receives coded or other energy from the source BC. Optionally, and as shown at X, a two-Winding transformer may be included in this connection for the purpose of insulating the two circuits from each other.

As long as the track relay TR remains actuated (which it does continuously during the periods that the associated track section is vacant), the r decoder supply transformer 28 is connected with the line circuit 3840 through the relay contacts G2 and 44. This, of course, causes the decoding apparatus to receive and respond to energy of the same character as is that supplied to the track circuit. When, however, the track relay drops its contacts to their unactuated positions, as when a train enters the section, the decoding appara tus is disconnected from the line circuit. Receiving no energy at all, it now causes the controlled signal S to show stop and the track circuit to the rear to be supplied with energy of the 80 or slow code.

In the case of signal blocks which include only a single track circuit, as does block D--E of the diagram, the line circuit 3840 receives only coded energy from the transmitter CT. When, however, a block includes, as does that shown at EF, a cut section of the character defined by location Ea, then the line circuit is carried through the contacts 42 and 44 of the track relay (see device TRa) at that block subdividing location. In such a case, provision is also made for connecting the rear portion of the line circuit, and the associated track transformer (see device TTa) which is energized therefrom, directly with the source of supply energy BC.

In the diagrams this provision is represented as comprising steady-energy supply conductors 43 and 45 joined to back-engaged points of the contacts 42 and 44 of the relay TRa. As will oecome more evident presently, this arrangement permits the track circuits of such cut sections rapidly to be cleared out or detectively operated upon their vacancy by a train. As here disclosed, moreover, the arrangement includes subject matter which is common to that disclosed and claimed in copending application Serial No. 230,- 083 filed September 15, 1938 by Ralph R. Kemmerer and Howell N. Dixon for Railway traflic controlling apparatus and assigned to the Union Switch and Signal Company.

For facilitating a later explanation of this track circuit clearing action, one typical manner in which the highway crossing .signals I3, shown as energy but also by pulses of coded energy of the being associated with the particular cut section represented at Ea, may be controlled will now be described, In the particular scheme represented, contacts 46 and 41 of the track relay TR at the entrance of the track section E--Ea are included in the actuating circuit of a local relay 48. This relay, in turn is provided with a contact 50 through which operating energy may be supplied to the signals I 3.

As long as the section EEa is unoccupied, relay TR at location E holds its contacts in their front-closed positions and thus completes the pick-up circuit for relay 48. The contact of that relay now occupies its picked-up or circuitopened position and the crossing signals I3 are unenergized and hence inactive. When, however, a train comes into the section, the contacts 46 and 41 of relay TR open the actuating circuit for relay 48, which, in turn, completes at contact 50 the operating circuit for the signals I3, thus causing them to warn the users of highway II that a train is approaching along the track I--2. This warning continues until the train moves out of the exit end of the section EEa, at which time track relay TR at location E again picks up and stops operation of the signals.

The various component parts of my improved signaling apparatus having been described, attention will now be directed to the manner of operation of the complete system shown in the diagram of Figs. 1ab.

When all of the protected blocks are unoccupied, the control and local windings I and 8 of each track relay receive energy of the I 88 code from the associated track and line circuits respectively. All of these relays maintain their contacts in the front-closed positions, thereby causing the line circuits 3840 also to transmit energy of the I80 code to the associated decoding equipments. Relays H and JA thereof are actuated, thus causing all of the controlled signals S to give the clear indication and the code transmitters CT to supply energy of the I80 code to the rails of the track sections immediately behind them.

In the case of single track section blocks, such as D-E of the diagram, the referred to transmission of the coded energy through the track and line circuits is directly from the transformers TT and X at the exit end of the section to the track relay windings and the decoding equipment at the entrance end of the section. In the case of signal blocks, such as EF, which contain one or more out sections, transformer T1 supplies only the rails of the forward track section while transformer X supplies, through conductors 38a and 40a and track relay contacts 42 and 44, energy of the I80 code to the transformer 'I'Ia connected with the exit end of the rear section (E-Ea) and the track relay and decoding equipment at the entrance end thereof.

In the event that a train occupies one of the sections of the protected stretch of track, the wheels and axles thereof shunt the trackway potential from between the rails and deenergize the control winding 7 of the track relay TR which is connected thereto. Winding 8 of that relay, which relay is at the first signal location behind the train, continues to receive energy from the line circuit 38-40 and in consequence the fly ball mechanism 9 is rapidly brought to a stop. This drops contacts 42 and 44 to their unactuated positions and disconnects the associated decoder supply transformer 28 from the line circuit. All three of the associated decoding relays H, J and JA now drop out their'contacts causing the controlled signal S to show the indication of stop and the transformers TT and X associated with the track section immediately to the rear to be supplied with energy of the 80 or "slow code.

At the second signal location behind the train, the track relay TR is actuated by energy of the 80 code received by its windings l and 8, and under the influence of this energy decoding relay H only is actuated. This causes the controlled signal S to show slow and the transformers TT and X associated with the track section in the immediate rear to be supplied with energy of the I20 or caution code.

At the third signal location behind the train, the track relay TR receives this energy and maintains the associated decoding equipment connected with the line circuit 3840. Decoding relays H and J are as a result actuated causing the controlled signal to show caution and the transformers TT and X associated with the track section to the immediate rear to be supplied with energy of the I80 code.

At the fourth and all subsequent locations (associated with unoccupied track sections) behind the train, the equipment has the condition previously described as resulting when all of the blocks of the protected stretch of track are unoccupied. That is, the controlled signal S shows clear and the code transmitter CT supplies energy of the I80 code to the track section in the immediate rear.

Cab signals carried by this train, assumed now to be passing through the otherwise vacant protected stretch of track I-2, are influenced by energy of the I80 code which is present in the portion of each unaccupied section ahead of the train and which causes correspondingly coded current to flow through the rails of that forward section portion. This current inductively transfers energy, through the before referred to pickup devices mounted on the locomotive front, to the train-carried control apparatus and causes the cab signals to show clear, thereby indicating that the three track sections immediately ahead are unoccupied.

Assume that while the first train continues to occupy a particular track section, a second train approaches from the rear. As this second train comes into the fourth, third, second and first track sections behind the first train, it will respectively receive from the wayside signal S associated with each section the usual visual indication of clear, caution, slow and stop and train-carried signals in the cab of its locomotive will be caused to show corresponding indications as the train advances into the successive sections named. This comes about in the following manner.

In entering each section, the train shunts the rails thereof and causes to flow therein from the transformer TT at the exit end of the section current of the particular coding which the associated decoding relays select in accordance with advance traffic conditions. For the third and succeeding sections behind the first train this energy is of the I80 or clear code, and for the second and first sections behind the one occupied by the first train, it is respectively of the I20 or caution code and the 80 or slow code.

As a train moves out of each track section, the removal of the interconnection of the rails of the section allows these rails again to transmit coded energy to the control winding I of the track relay TR at the entrance end of the section. The local winding 8 of that relay continues to receive similarly coded energy from the line circuit 3840. The combined energization named imparts rotation to the fly ball mechanism 3 of the relay and within a short space of time brings it up to full speed. The resulting front closure of the track relay contacts reestablishes the connection of the decoding apparatus with the line circuit and thereby restores the equipment at the associated signal location to its normal unoccupied track section condition.

The foregoing description of the operation of the improved signaling system of my invention has been made on the basis of single track circuit signal blocks and has not attempted to treat the special features occasioned when the blocks are provided with two or more track circuit sections such as are represented at E-Ea and Ea-F. Insofar as the control of the equipment at the associated signal locations E and F is concerned, the presence of the cut section Ea makes no difference whatever. stretch of track is unoccupied, the cut-section track relay TRa completes, through its contacts 42 and 44, a connection of line circuit conductors 3B and 48 with conductors 38a and 48a and thereby permits the equipment at location F to act upon the equipment at location E in exactly the same manner as were the track rails not divided at Ea.

When, however, a train passes through the multisection block, there are caused to take place certain added or distinctive operations which will now be described. Occupation of the section EEa causes the track relay TR at location E to drop out its contacts in the usual manner, disconnecting the associated decoding apparatus from the line circuit 384El and opening, through contacts 46 and 41, a circuit which causes the highway crossing signal l3 to be placed in operation. During this operation, both the track and line circuits which are identified with this particular section continue to receive coded energy from line conductors 33a and 40a.

As the front portion of the train enters the section EaF, track relay 'I'Ra drops out its contacts thereby shifting the connection of the line conductors 38 and 4!! from the line circuit sea-sea to steady energy supply conductors 43 and 45. Through transformer TTa, steady energy now is transmitted to the rails of track EEa and through the direct connection indicated it is also impressed upon the local winding 8 of the track relay TR at location E. As long, however, as any portion of the train remains within the section E-Ea no control effects are produced by this steady energy.

As the rear portion of the train vacates this rear track section of the block E-F, control winding 1 of track relay TR at location E also receives steady energy causing the fly ball device 9 rapidly to be set in motion and raising the relay contacts to their front-closed positions within a very short space of time. This discontinues operation of the highway crossing protective signals I3 by energizing relay 48 and reconnects the decoder supply transformer 28 with the line circuit conductors 33 and 48. That transformer now transmits the steady energy from circuit 38,48 to the code following relay CR which in consequence continuously holds its contact 30 in the front-closed position thereby causing steady direct current to be circulated through the primary winding of the decoding transformer DT. Such. unvarying current, of course, trans- If the protected fers no energy to the secondary winding and, in consequence, all three of the decoding relays H, J and JA continue to remain unactuated.

Controlled signal Se accordingly continues to display the indication of stop and transformers TT and X continue to supply the track and line circuits identified with the section D-E with energy of the 86 slow coding. Except for the fact that the track relay is caused to pick up its contacts more rapidly, the effect produced by impressing this steady energy upon the line circuit Sshit for the section E-Ea is exactly the as were coded energy to be used for this purpose and the decoding equipment to be maintained disconnected from the line circuit or otherwise arranged to receive no energy at all.

As long as any portion of the train remains an'thin the track section EaF, the just described supply of steady energy to the line circuit 38-40 is continuous. Upon vacation of the section by the train, track relay TRa picks up its contacts, under the influence of coded energy supplied to its windings i and 8 from the transformers TT and X at location F, and reconnects the line circuit conductors 38 and 48 with the conductors 38a and 4%. This places the equipment at location E directly under the control of the equipment at location F and initiates operations already described in detail in connection with the signal blocks which contain only a single trackcircuit section.

In the arrangement shown in Figs. 1ab the voltage of the steady energy which is supplied through conductors 43 and 45 to the track and line circuits identified with the rear section EEa is of the same magnitude as is that which is impressed upon the line circuits through the contacts of the code transmitter CT. Clearing out of the track circuit identified with the rear section of signal blocks such as EF is, due to the continuous characteristics of this energy, effected more rapidly than were coded energy to be used for this purpose. In cases where it is desired further to speed up this clearing out operation, an arrangement such as is shown in Fig. 3 may be employed.

There I have represented a step-up trans former, shown as consisting of but a single winding 52, included in the circuit through which power source terminals B and C supply energy to the conductors 43 and 45 associated with the cut-section track relay 'IRa. The result of this elevated voltage thus supplied through the line circuit 38-49 is, of course, to increase the intensity of energization of the windings 1 and 8 of the track relay TR at location E and thus cause it to pick up its contacts in an even shorter time when a train moves out of the exit end of the section EEa.

It will be apparent that the improvements of my invention which have just been described may be applied to signal blocks including cut sections occasioned by devices or conditions other than the intersecting highway shown at H in Fig. la. Detector track circuits associated with interlocked switches and other equivalent appli cations may be cited in this connection. In all instances, however, the operation of the improved signal control equipment of my invention will be the same as or closely comparable to that just described in detail. In the interlocked switch application referred to, application of the steady energy in the improved manner evolved by me permits the switch associated with the detector circuit quickly to be released in advance of the time that an associated signal is permitted to clear.

The improved signaling system herein disclosed is inherently self-protecting against the giving of false indications due to a breaking down of the insulated joints 3 which electrically separate the track rails of adjacent track-circuit sections. Such failure, of course, permits track circuit current from a block in the rear, for example, to flow into the track rails of a block ahead thereby tending to create a potential false clear or other less-restrictive indication.

This protection results from the inherent characteristics of the centrifugal type track relays TR together with the novel form of energy supply therefore which I have disclosed and described herein. It has been seen that a centrifugal type of track relay is capable of picking up its contacts only when the control and local windings 1 and 8 thereof are energized simultaneously by alternating voltages of the same frequency and bearing a definite phase relation and that other forms of energization tend to retard rather than produce rotation of the fly ball device 9.

In the particular arrangement shown, the requirement for coincidence of winding energization is depended upon to effect the named protection againstbroken-downinsulatingrailjoints. Should any one of these joints 3 break down, the current conducted therethrough to an adjacent track circuit within a stretch of the track then under the control of a train will be of a different coding than that of the coded current operating in this adjacent circuit. Since the energy pulses of these two different codes are necessarily non-coincident, this externally received energy will be completely ineffective as far as instituting actuation of the track relay TR is concerned.

It will thus be seen that in the improved arrangement of my invention, should the code of one track section pass over defective rail joints into the adjoining section, a restrictive signal will be displayed and the giving of a false clear or other less-restrictive indication will thus effectively be prevented. In obtaining the protection above discussed, it is also preferable to stagger the relative instantaneous polarities of adjacent track circuits in the manner indicated by the plus and minus markings above the track section rails. This eliminates the possibility of Y only when the signaling system employs track relays of the two-winding type now shown at TR and not when these track relays are of some other design that is not capable of distinguishing joint leakage energy from the normal signal control energy in the track circuit.

Another advantage of track relays of the two element centrifugal type is that the fly ball elements 9 thereof have a relatively high rotative inertia which prolongs their rotation for some time following each relay deenergization. Because of this characteristic no special expedients need be resorted to to provide a slowness of contact release which is sufiicient to bridge the intervals between successive pulses of the coded energy with which the relay is supplied from the track rails.

Another advantage of my improved system which accrues, when a double-end feed system of power-supply transmission isuse-d, is that in the case of a break in the transmission line the system will continue to operate as a whole without giving any stop or false proceed wayside or cab signal indication. In such an event, energy continues to be supplied to the terminals B and C at all of the track section-dividing locations and operation takes place in exactly the same manner as had the break in the transmission line not occurred.

My invention further contemplates improvements in the organization and arrangement of the apparatus comprised by the decoding equipment through which actuating currents are supplied to the relays H, J and JA by Way of the frequency selective circuits 32. These improvements are depicted in the upper portion of Fig. 2 and in their broad objective they are generally similar to the non-moving part decoding equipment that is disclosed and claimed in copending application Serial No. 161,784, filed on August 31, 1937 by Herman G. Blosser for Railway trafiic controlling apparatus and assigned to the Union Switch and Signal Company.

In the improved decoding scheme which I have represented in Fig. 2, the primary winding of the decoding transformer DT is directly connected with the rectifier 29 through which the transformer 28 supplies coded energy to the equipment. This form of connection eliminates the use of the conventional code following relay shown at OR in Figs. 1ab and the pole-changing direct current circuits of which the contact 30 of this relay forms a part.

In operation of the apparatus shown in Fig. 2, coded pulses of alternating current energy transmitted through transformer 28 are rectified by rectifier 29 and thereby converted into corresponding pulses of direct current energy. These cause to flow through the primary winding of the decoding transformer DT corresponding surges of unidirectional current. These surges, in turn, cause the energizing circuits of the decoding relays H, J and JA to have impressed thereon an alternating current voltage of the same frequency in cycles per minute as is the coded trackway energy which at the time is supplied to transformer 28.

This comes about from the fact that as each surge of direct current energization is first applied to the decoding transformer DT the primary current builds up in the increasing direction and induces in the secondary winding a half-wave of alternating current voltage of one polarity. At the termination of each of the surges of direct current, the primary current changes in the decreasing direction thereby inducing in the secondary a half-wave of alternating current voltage of opposite instantaneous polarity. Accordingly, the scheme of Fig. 2 operates in a manner which is exactly equivalent to the conventional arrangement pictured in Figs. lab. It requires, however, that the transformer 28 directly transmit sufii'cient energy to effect actuation of the decoding relays and thus calls for a somewhat higher capacity in the devices 28 and 29.

While I have described my invention as being incorporated in apparatus which supplies only three train governing codes to the trackway, it will be understood that my improved equipment may readily be adapted to other applications wherein provision is made for either more or less than three different governing indications. Likewise, while I have restricted my disclosure to train control systems employing track relays of a particular frequency selective form especially suited for connection to electric propulsion tracks, it will be apparent that the broad improvements of my invention are equally applicable to train control systems employing track relays ,of other types.

Although I have herein shown and described only one form of railway trafiic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

i. In combination, a signal-block length of railway track including a forward .and a rear track section, means for supplying coded energy to the rails of said forward section, decoding apparatus associated with said rear section, a line circuit through which energy may be supplied to the rails of said rear section and to said decoding apparatus, and a track relay connected'to said forward section rails and arranged 'to connect said line circuit with said coded-energy supply means when said "forward section is vacant and with a source of steadyienergy when said forward section is occupied.

2. In combination, .a signal-block length of railway track including 'a forward and a rear track section, means for furnishing coded energy to theLraiIs of said forward section, decoding .apparatus associated with said rear section, a line circuit through which energy :may be supplied to the rails of said rear section and to said apparatus,.a trackrelay connected to said forward section-rails and arranged -to connect said line cir cuit with said .coded-energy-supply means when said forward section is vacant and with a source of steady energy when said forward section is occupied, anda track relay connected to said rear section rails and arranged to disconnect said decoding apparatus from said line circuit when said rear section is occupied.

3. In combination, a signal block-length of railway track including a forward and a rear track section, a track relay connected to the rails of each of said sections, a code transmitter connected to supply codedenergy to the rails of said forward section, decoding apparatus associated with said .rear section, a line circuit through which energy may be supplied to the rails of said rearsection and to said apparatus, contacts carried by the forward-section track relay for connecting said iine circuit with the code transmitter when the forward section is vacant and with a source of steady energy when the forward section is occupied, and contacts carried by the rear-section track relay for disconnecting the decoding apparatus from the line circuit when the rear section is occupied.

4. In combination, a forward and a rear section of railway track, a wayside signal positioned at the traffic-entering end of said rear section, decoding apparatus for controlling the operation of said signal, means responsive to trafiic conditions for supplying the rails of said forward track section with coded energy suitable for influencing train-carried cab signals, a line circuit through which energy may be supplied to the raiis of said rear track section and to said decoding apparatus, a track relay connected to the rails of said forward section and arranged to connect said line circuit with said coded-energysup' y means when said forward section is vacant and with a source of steady energy when said section is occupied, and a track relay connected to the rails of said *rear section and arranged to disconnect-said decoding apparatus from the line circuit when said rear section is occupied.

5. In combination, a signal-block length of railway track including va forward and rear track section, a track relay associated with each ofsaid sections and providedwith a control windingconnected tothe'rails thereof and with a local winding, means for supplying coded energy to the rails of the forward track section and to the local winding of the track relay associated therewith, a line :circuit through which energy may be transmitted to the rails of the rear track section and to the local winding of the track relay associateditherewith, and means controlled by forward-section track relay for connecting said line-circuit with said coded-energy-supply means when said forward section is vacant and with a source of steady energy when said forward section is occupied.

6. In combination, a signal-block length of railway track including a forward and a rear track 'section, atrack relay associated with each of :said isections andprovided with a control winding connected to the trafiic-entering-ends of therails thereof and with'a local winding, .a code transmitter connected 'to supply coded traincontrol energy to "the -traffic-leaving ends of the rails of said forward section, a line circuit for transmitting to the local Winding of the forwardsection track relay similarly coded energy from said transmitter, other circuits through which energy may be transmitted to the traffic-leaving ends .of the rails of said rear track section and to the local winding of the rear-section track relay, and means controlled by the forward-section track irelay for connecting said other circuits with said line circuit when said forward section is zvacan't and with a source .of steady energy when said :forward section is occupied.

:7. In combination, a forward and a rear section of railway track, a wayside signal positioned at the ti anic-entering end of said rear section, decoding-apparatus for controlling the operation of :said signal, :means responsive to t'raffrc conditions for supplying the rails of said forward track .section with coded train-control energy, a track relay associated with each of said sections and provided with .a control winding connected to ;the rails thereof and with a local winding, a line circuit connecting the local winding of the forward-section track relay with said coded-energy-:supply means, other circuits through which energy may be transmitted to the rails of said rear track :section, to the local winding of the rear-section track relay and to said decoding apparatus, contacts carried by said forward-section relay for connecting said other circuits with said line circuit when the forward section is vacant and with a source of steady energy when the forward section is occupied, and contacts carried by the rear-section track relay for disconnecting the decoding apparatus from its supply circuit when the rear track section is occupied.

8. In combination, a section of railway track, a wayside signal positioned at the entrance of said section, a track circuit including the rails of said section, a line circuit, means responsive to advance traffic conditions for supplying coded energy to said track and line circuits, decodin apparatus connected with said line circuit but not with said track circuit and responsive to the energy therein for controlling said signal, and. a track relay energized from said track circuit and arranged to interrupt said apparatus connection Whenever said section is occupied.

9. In combination, a section of railway track, a line circuit, means for furnishing coded energy to the rails of said section and to said line circuit, decoding apparatus, and a track relay operated by energy received from said rails and arranged to connect said apparatus with said line circuit at all times except when said section is occupied.

10. In combination, a stretch of railway track divided into a plurality of successive sections, a wayside signal positioned at the entrance of each section, decoding apparatus for controlling the operation of each of said signals, a track circuit including the rails of each section, a line circuit associated with each section, means responsive to advance traific conditions for supplying each of said track and line circuits with coded energy suitable for influencing train-carried cab signals, and a track relay energized from each track circuit and arranged to connect the associated decoding apparatus with the associated line circuit at all times except when .the associated section is occupied.

11. In combination, a section of railway track, a track relay provided with a control winding connected to the rails of said section and with a local winding, means for supplying coded traincontrol energy to said rails, a line circuit connecting the local winding of said relay with said supply means, decoding apparatus, and means controlled by said relay for connecting said apparatus with said line circuit at all times except when said section is occupied.

12. In combination, a section of railway track, a track relay at the traflic-entering end of said section provided with a control winding connected to the rails thereof and with a local winding, a coding device arranged to supply coded traincontrol energy to said rails at the traffic-leaving end of the section, a line circuit connecting the local winding of said track relay with said device, decoding apparatus at the trafiic-entering end of the section, and a contact carried by said track relay for connecting said apparatus with said line circuit at all times except when said section is occupied.

13. In combination, a plurality of successive sections of railway track, a track relay associated with each of said sections and provided with a control winding connected to the traific-entering ends of the rails thereof and with a local winding, a code transmitter for supplying coded traincontrol energy to the trafiic-leaving ends of the rails of each of said sections, a line circuit for transmitting similarly coded energy to the local winding of each associated track relay, decoding apparatus for selecting the coding of the energy which is supplied from each of said transmitters, and means controlled by each of said track relays for connecting the associated decoding apparatus with the local-winding supply circuit for that relay whenever the relay-connected track section is unoccupied.

14. In combination, a section of railway track, means including a coding device for supplying the rails of said section with train-control energy of one or another of a plurality of diiierent codes, decoding apparatus adapted to respond distinctively when energy of each of said codes is received thereby, a track relay provided with a control winding connected to said section rails and with a local winding, a line circuit for supplying said local winding with energy from said device coded in the same manner as is that supplied to the track rails, and means controlled by said track relay for connecting said decoding apparatus with said line circuit at all times except when said section is occupied.

15. In combination, a section of railway track, means for supplying coded energy to the rails of said section, trafiic-governing apparatus, a decoding relay for controlling said apparatus, a decoding transformer provided with an output circuit which supplies energizing current to said relay, a track relay provided with a control winding connected to said section rails and with a local winding, a line circuit for supplying said local winding with energy coded in the same manner as is that supplied to the track rails, and means rendered efiective by said track relay at all times except when said section is occupied for causing said decoding transformer to receive a measure of the energy present in said line circuit.

16. In combination, a section of railway track, means for supplying coded energy to the rails of said section, a decoding transformer, train-controlling apparatus operably governed by the output voltages of said transformer, a code-following relay, a circuit controlled by said relay for supplying energizing current to said transformer, a line circuit for supplying said relay with energy coded in the same manner as is that supplied to the track rails, and a track relay energized from said rails and arranged to disconnect said codefollowing relay from said line circuit when said section is occupied.

CHARLES W. FAILOR. 

